The present invention relates to a new and distinct variety of Buddleja (butterfly bush) grown as an ornamental shrub for home and commercial landscapes. Butterfly bush is typically grown for its attractive, fragrant flowers that are borne throughout the growing season.
The new and distinct variety of butterfly bush resulted from a formal breeding program established by the inventors in Raleigh, N.C., United States. One of the objectives of the breeding program was to develop a dwarf, spreading Buddleja with white flowers. ‘Ice Chip’ was selected at a research station in Jackson Springs, N.C. in 2006 from a population of 357 seedling progeny derived from a hand pollinated cross of ‘Blue Chip’ (female parent: NCSU cultivar tested as NC2004-9, U.S. Plant Pat. No. 19,991)×NC2002-12 (male parent) made in 2005 in Raleigh, N.C. ‘Blue Chip’ is a complex hybrid containing 3 different species and one botanical variety of Buddleja (B. davidii, B. davidii var. nanhoensis, B. lindleyana, and B. globosa). NC2002-12, the other parent of ‘Ice Chip’, is a hybrid of ‘White Ball’×‘Nanho Purple’. ‘Nanho Purple’ is a variety derived from Buddleja davidii var. nanhoensis. ‘White Ball’ is a complex hybrid, presumably containing B. davidii and B. fallowiana. The pedigree of ‘Ice Chip’ is shown in Table 1. Of all the parents used in the development of ‘Ice Chip’, the varieties ‘Blue Chip’, ‘White Ball’, ‘Nanho Purple’, and ‘Honeycomb’, and the species Buddleja lindleyana are available in commerce.
TABLE 1Pedigree of Buddleja ‘Ice Chip’.
The seeds resulting from the 2005 controlled hybridization process were harvested in fall of 2005 and germinated in a greenhouse in Raleigh, N.C. in the winter of 2006. The resulting 351 seedlings were planted in field trials in spring of 2006 at a research station in Jackson Springs, N.C. These plants flowered in summer 2006, and one plant, designated NC2006-10, was selected for its dwarf plant size, spreading habit, attractive white flowers, and lack of seed set (female sterile). This original plant demonstrated characteristics identical to those subsequently expressed on other plants when propagated from stem cuttings. This single plant is the subject of the present invention Buddleja ‘Ice Chip’.
The distinguishing traits of ‘Ice Chip’ include at last one of dwarf plant size, spreading growth habit, gray-green leaf color, attractive white flowers, male sterility and female structures that are essentially sterile. “Essentially sterile” is used because applicants do not preclude the possibility that a seed set may be observed on rare occasions. Ideal cultural conditions for ‘Ice Chip’ include well-drained soil, full sun, and moderate moisture. ‘Ice Chip’ exhibits no serious pest or disease problems known to the inventors, except for occasional spider mite infestation during periods of hot, dry weather.
The closest comparison known to the inventors are the varieties ‘Blue Chip’ (U.S. Plant Pat. No. 19,991), ‘White Ball’ (non-patented), and ‘Podarus 15’ (U.S. Plant Pat. No. 22,143). Plants and flowers of this new variety differ from ‘Blue Chip’. In direct comparisons of ‘Ice Chip’ and ‘Blue Chip’ in the inventor's experimental trials, plants of ‘Ice Chip’ are consistently more spreading, more highly branched, more dense, and have white flowers, compared to the blue flowers of ‘Blue Chip’. ‘Ice Chip’ is distinctly different from ‘White Ball’. In direct comparisons of ‘Ice Chip’ and ‘White Ball’ in the inventor's experimental trials, plants of ‘Ice Chip’ are consistently more spreading as compared to the globose architecture of ‘White Ball’. ‘Ice Chip’ is shorter in height and has greater width as compared to ‘White Ball’. In replicated trials of 10 plants of both varieties, two-year-old unpruned plants of ‘Ice Chip’ attained a height and spread of 48.4 and 125.8 cm, respectively (height/width ratio=0.36), after two years of growth. Plants of ‘White Ball’ attained a height and spread of 79.7 cm and 100.6 cm (height/width ratio=0.79), respectively. Plants of ‘Ice Chip’ are different from ‘Podarus 15’. In side-by-side comparisons in the inventor's experimental trials, plants of ‘Ice Chip’ are shorter, have greater branching, and show a denser growth habit as compared to ‘Podarus 5’ after one full year of growth.
The inventors conducted the first asexual propagation of ‘Ice Chip’ in fall 2006 in Raleigh, N.C., and ‘Ice Chip’ has subsequently been propagated in the same location in years 2008, 2009, and 2010. In all cases, the original plant selection was propagated asexually by softwood to semi-hardwood stem cuttings. Such cuttings root readily under mist in about 14 to 21 days, and resume normal growth. Ten plants derived from stem cuttings of the variety were established in experimental test plots in Jackson Springs, N.C. in 2007. During all asexual propagation, the characteristics of the original plant have been maintained. Plants derived from stem cuttings exhibit characteristics identical to those of the original plant, and no aberrant phenotypes have appeared.
Test plantings and performance evaluation over six years at a research station in Jackson Springs, N.C. demonstrate this variety to be relatively consistent in its characteristics even under the different growing conditions associated with yearly climatic variation.
Plants of the new variety are very dwarf after establishment in the field, being less vigorous and more dwarf than most varieties of butterfly bush in commerce. Young plants have averaged about 24.2 cm of height growth per year. Plants are spreading in growth habit. Flowering occurs in the first year of growth on newly formed wood. The inflorescence is a panicle, and shows a white flower color. Flowering usually begins in early June in Jackson Springs, N.C., and continues throughout the growing season until the first freeze event in October or November. An individual inflorescence flowers for about 7-10 days, depending on temperature, but new flowers are made during the entire growing season. The new variety produce no functional male flower parts, and hence makes no pollen. Female fertility of flowers is considered to be essentially sterile, as the new variety sets virtually no seed in a field or landscape setting, an asset in landscape plantings.
‘Ice Chip’ is distinguished from other related known varieties based on the unique combination of traits including dwarf growth, spreading habit, white flowers, male sterility, and female structures that are essentially sterile.
The new variety has been named the ‘ICE CHIP’ cultivar. First public offer for sale of ‘Ice Chip’ was made in Grand Haven, Mich., U.S.A. on Aug. 1, 2011.